RightWay GPS Navigator RW 430 Guia do Utilizador descarregar pdf (Página 86)

Glossary

GPS RTK Base GPS Receiver User Guide

carrier A radio wave having at least one characteristic (such as frequency,

amplitude, or phase) that can be varied from a known reference value by

modulation.

carrier

frequency

The frequency of the unmodulated fundamental output of a radio

transmitter. The GPS L1 carrier frequency is 1575.42 MHz.

carrier phase Is the cumulative phase count of the GPS or GLONASS carrier signal at a

given time.

cellular

modems

A wireless adaptor that connects a laptop computer to a cellular phone

system for data transfer. Cellular modems, which contain their own

antennas, plug into a PC Card slot or into the USB port of the computer and

are available for a variety of wireless data services such as GPRS.

CMR

CMR+

Compact Measurement Record. A real-time message format developed by

Trimble for broadcasting corrections to other Trimble receivers. CMR is a

more efficient alternative to RTCM.

covariance A statistical measure of the variance of two random variables that are

observed or measured in the same mean time period. This measure is equal

to the product of the deviations of corresponding values of the two variables

from their respective means.

datum Also called geodetic datum. A mathematical model designed to best fit the

geoid, defined by the relationship between an ellipsoid and, a point on the

topographic surface, established as the origin of the datum. World geodetic

datums are typically defined by the size and shape of an ellipsoid and the

relationship between the center of the ellipsoid and the center of the earth.

Because the earth is not a perfect ellipsoid, any single datum will provide a

better model in some locations than in others. Therefore, various datums

have been established to suit particular regions.

For example, maps in Europe are often based on the European datum of

1950 (ED-50). Maps in the United States are often based on the North

American datum of 1927 (NAD-27) or 1983 (NAD-83).

All GPS coordinates are based on the WGS-84 datum surface.

deep discharge Withdrawal of all electrical energy to the end-point voltage before the cell or

battery is recharged.

DGPS See real-time differential GPS.

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